The present invention relates to cases for axles having a universal joint such as axles for transmitting power to steering and propelling wheels as employed in various tractors for agriculture and civil engineering.
Cases for axles having a universal joint must be flexible at the joint portion. Usual axle cases therefore comprise two semispherical members having different diameters and a tube integral with one of the semispherical members. Both the members cover the universal joint and are connected together rotatably relative to each other in the direction of flexion of the universal joint, with the tube housing the axle connected to the universal joint.
Because the semispherical members must be rotatable relative to each other, the tube invariably has a smaller diameter than the semispherical member connected thereto, this resulting in the drawback that the junction between the tube and the semispherical member has low strength. Especially in the case of tractors for use in agriculture and civil engineering, the axle case is by nature subject to a heavy load, which causes a stress concentration in the junction and possibly leads to deformation and break.
Such a drawback may be remedied with the use of a strong tube of larger diameter which is integral with a semispherical member having a correspondingly enlarged diameter. However, the enlarged structure materially increases both the size and weight of the axle case itself, and the case becomes difficult to make and handle, renders the tractor body heavier and involves various other objections.
As will be apparent from the above description, it is desired that axle cases of this type be made compact and lightweight to the greatest possible extent and have a tough junction between the tube and the semispherical member, whereas none of the conventional axle cases are satisfactory in these respects.